This invention relates to position encoders of the type utilizing energy emitters and receptors with a position coded mask interposed in the transmission paths between the emitters and receptors.
Position encoders are well known in the prior art for providing an indication of the position of a movable element. In one class of encoders known as absolute angle encoders, a rotatable code element such as a disc has a plurality of sensible codes arranged therearound, these codes being read by an associated sensor to provide an output indication of the angular position of the code element about its rotational axis. The particular codes employed can take a variety of forms to suit particular operating requirements, and can include optically, magnetically or electrically sensible coding arrangements which are per se well known in the art. In such prior art arrangements, the codes are typically arranged along a plurality of tracks, with the tracks being sensed in a parallel fashion. Thus, the prior art has typically required one sensor per track. A disadvantage with such an arrangement is the cost involved with the sensors.
It is therefore an object of this invention to provide a position encoder with an efficient utilization of sensing elements.